Magnetic selecting device



Aug. 9, 1960 J. D. LAWRENCE, JR

MAGNETIC SELECTING DEVICE Filed May 23, 1955 2 Shee'es-Shee1'l 1 JOSEPH D. LAWRHVGE, JR.

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AGENT Aug. 9, 1960 J. D. LAWRENCE, JR 2,948,883

MAGNETIC SELECTING DEVICE Filed May 23, 1955 2 Sheets-Sheet 2 o qfmr v FG. 3.

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AGENT MAGNETIC sELEcrING DEVICE Joseph D. Lawrence, Jr., Philadelphia, Pa., assignor to Sperry Rand Corporation, a corporation of Delaware Filed May 23, 1955, Ser. No. '510,223

16 Claims. (Cl. 340-174) This invention relates to magnetic selecting devices. It has heretofore been explained how a selected core of a group may be switched from one magnetic state to another in response to predetermined signals at a given input. Such systems are valuable in many situations but it is also valuable to have systems in which upon selection of a given binary input number all the cores except the one selected are switched. The prior art has not explained how this could be done. One object of this invention is to provide a system whereby all but the selected magnetic element of an array are switched in response to a given binary input signal.

Another object of the invention is to provide a system as described in the previous object which is low in cost as well as effective in operation.

A still further object of the invention is to provide a system, according to the first object, which is reliable in operation and does not have any parts likely to burn 0111;.

Another object of the invention is to provide a system of the foregoing type which is simpler in construction and operation than prior systems. p

In carrying out the foregoing objects, l provide one core for each different output and a series circuit for each input digit. Each input series circuit has a coil wound on each core. The direction in which the coils are wound, which coils are energized, and the strength of a biasing magnetizing force applied to each core, determines the switching of the cores. By an arrangement hereinafter fully explained, it is possible to switch all cores except the selected one.

In the drawings:

Figure 1 is a hysteresis loop of the material used in the several cores.

Figure 2 is a schematic diagram of the apparatus con-r stituting the invention. K

Figure 3 is a modified form of the ydevice of Figure 2. Figure 4 is another modified form of the device of Figure 2.

The magnetic cores may be made of a varietyof matenitecl tates Patent core may be constructed in a number of geometries in- Y oluding both closed and open paths; for example, cupshaped, strips, and toroidal-shaped cores are possible. Those skilled in the art understand that when thecore is operating on the horizontal (or substantially saturated)A Patented Aug. s, r1960 dice Forexample, if both switches 12 and 13 remain open,l

this would be va selection of the 00 core and hence it would not be ipped but the remainder would be. As another example, if the switch 12` remained open and switch 13 was closed, this would .be a selection of the (i1 core and hence it would not be ipped but the `rest would be. Connected to the output of switch 12 is a resistor 15 and a negative source 14 which normally biases rectifier 41 to cut olf `and prevents iiow of current in the input circuit except during the interval that switch 12 is closed. The series circuit including switch 12 also includes coils 16, 17, 18 and 19 wound on the four cores respectively. The direction in which these coils are4 wound is important as will hereinafter appear. There is another series circuit including switch 13 and which has rectiiiers and input biasing means equivalent to that described in connection with the first-mentioned circuit. This second series circuit also has coils 20, 21, 22 and 23 wound in suitable directions as will hereinafter appear. A` third series circuit which carries what will hereinafter be described as the bias pulse, includes coils 24, 25 and 26 all wound in the same direction but having different numbers of turns for purposes that will appear. Output and voltage regulating windings 27, 28, 29 and 30 are respectively on the four cores and these four coils have four output terminals 31, 32, 33 and 34 respectively. Each output circuit has a potential limiting device 35-36 connected `to it for purposes hereinafter described. A restore circuit having coils 37, 38, 39, 40 and rectier 42 is also employed. y

If it now be assumed that source PP-I is about to go positive and that all the cores are at negative remanence, if switches 12 and 13 are to remain open, it is obvious that core 00 is the selected core andthat it will not be switched but that all others will be. Therefore, in response to the next positive excursion of source PP-l, no current will ow in any of coils 16 to 23 inclusive butv current will flow in coils 24, 25 and 26. The flow of current in the latter three coils will switch cores 01, 10 and V11 to positive saturation, inducingpotentials in the output coils 28, 29 and 30. Therefore output signals will appear at 32, 33 and 34 but there will be no potential induced in coil 27 and no output at terminal 31 since there was no magnetizing force on core 00 to switch it. During the next negative excursion of sourcePP-l, current flows through rectier 42 and coils 37, 38, 39 and 40 and restores all of the cores to negative remanence.

Assume that during the `next positive excursion it isl negative magnetizing forceson cores 01 and 11 due to coils 21 and 23. The negative magnetizing force of v. coil 21 is, however, cancelled by the positive magnetizing A force of coil 24 leaving'core 01 with a net magnetizing force of zero. The positive magnetizing forces of coils 25 and 26 respectively add to those of coils 22 and 23.

Hence core 00 is switched due to the positive magnetizing force of co'il20`, core 10 is switched due to the positive magnetizing forces of coils 22 and 25, and core 11 is` switched since the positivemagnetizing force of coil 26 is greater than ythe negative magnetizing force of coil 23 thus causing the core 11to experience a net positivemagnetizing force, As a result, all the cores except 01 In this case there are positiveV magnetizing. forces on cores 00 and 10 due to coils 20 and 22, and

are switched whereby potentials `are induced in coils 27, 29 and 30, producing outputs at 31, 33 and 34. At the conclusion of the positive excursion of source PP-1 which performed the aforesaid switching operations, the next negative excursion of that source will pass current through coils 37 to 40 inclusive, restoring all the cores to negative remanence. n

If it now be assumed that binary number is fed into the system by closing switch 12 and leawng switch 13 open, current will ow through coils 16 to 19 inclusive but not through coils 20 to 23 inclusive. There will be no net magnetizing force in core 10 since coil 18 produces a nega-tive magnetizing force and coil produces a positive magnetizing force. Therefore, core 10 is not switched and no potential is induced in coil 29.v However, the iiow of current in coil 16 will switch core 00 andthe ow of currents in coils 17 and 24 willswitch core 01. Core 11 will be switched since the negative magnetizing force of coil 19 is overcome by the very large positive magnetizing force of coil 26 and the latter switches this core to positive saturation. Hence, potentials are induced in coils 27, 28 and 30. At the conclusion of the positive excursion of source PP-l which performed the aforesaid core switching operations, the next negative excursion of that source will pass current through coils 37 to 40 inelusive, restoring all the cores to negative remanence.

If it next be assumed that binary signal 11 is to be fed into the system by closing switches 12 and 13, the next positive excursion of source PP will energize all of coils 16 to 26 inclusive. There will, however, be no net flux in core 11 since the coils 19 and Z3 combined will produce a magnetizing force of -ZF while coil 26 will produce a magnetizing force of -l-2F. Hence there will be no change of ux in coil 30. There will be a magnetizing force of -l-F applied to core 10, since coils 22 and 25 apply positive magnetizing forces equal to -l-ZF while coil 18 applies only a negative magnetizing force equal to -F. Hence the net magnetizing force of l-F switches this core to positive saturation and in so doing induces potential in coil 29. There will be a switching of core 01 since coils 17 and 24 apply a positive magnetizing force of 2F to the core which switches it to positive saturation and in so doing induces potential in coil 28, notwithstanding the negative magnetizing force of -F due to coil 21. Both coils 16 and 20 apply positive magnetizing forces to core 00 thus switching it to positive saturation and in so doing induces potential in coil 27. During the next negativeexcursion of source PP-Lthe flow of current through coils 37 to 40 inclusive restores the device to negative remanence.

While the aforesaid device has been illustrated as having only two inputs and only four outputs, this may be greatly expanded by having any number of outputs together with the proper number of inputs therefor. In the case of such expanded systems, the number of turns of the coils in the bias pulse circuit must be altered somewhat, but there is no dithculty in determining what this arrangement should be by following the teachings already given above. It is also possible to carry out the invention by having some of the coils of the input circuits have diierent numbers of turns from those of other coils of input circuits.

In Figure 2 the limiters such as 35--36 limit the rate of change of flux in the core and thus limit any back voltages induced in unused input circuits.

rIn the embodiment of the invention described in Figure 2, no output circuits have been described which have gain. There are, however, output circuits which make power gain possible. Figures 3 and 4 illustrate two of these possible output arrangements. In these two figures the device is identical with that of Figure 2 except that certain parts have been added to the left of the vertical line A-A of Figure 2.

For example, in Figure 3, the cores are operated as series-,type magnetic pulse ampliers in which Acase each corerwill have an output circuit. The output circuits for core 00 includes load 44, coil 45, rectifier 46 and source PP2. Sources PP-1 and PP-Z would, in this case, be squarewave alternating current generators that are out of phase with each other so that one is going positive when the other is going negative, and vice versa. When the additional structure of Figure 3 is added to the device of Figure 2, the coils 37 to 40 inclusive of Figure 2 may be omitted.

The operation of the device of Figure 3 is as follows. After all but one core has been set to positive remanence -l-Er by source PP-1, as previously described in connection with Figure 2, source PP-Z applies a positive pulse to all of the output circuits, placing a negative magnetizing force on all four of the cores. The selected core, which was allowed to remain at negative remanence, will be in its low impedance state, thus passing current from source PP-Z to its respective load. All other cores will be in a high impedance state and will oppose the ow of current to their loads. Hence, only the selected load will be energized. This system will have power gain, that is, the load circuit may be so arranged that the change in power at the load will be much greater than the change in power required at the address inputs.

Figure 4 shows another output circuit applicable to this invention, and it uses the cores as parallel-type magnetic pulse amplifiers which have power gain. Such an embodiment would utilize, on each core, an output coil in series with a rectifier and a load. These parts respectively bear reference numbers 47, 48 and 49 on the core 00 of Figure 4. The rectifier 4S disconnects the load 49 from the coil 47 during the setting operation, when source PP-1 is positive, because of the negative potential induced in coil 47 when the core is switched to positive remanence. When current flows through coils 37 to 40, all but the selected core switch from positive remanence to negative saturation, thus inducing positive potentials in their output coils 47, driving current through their loads 49. The selected core already will be at negative remanence so there will be no output induced in its coil. Thus all but one core have an output.

I claim to have invented:

1. In a switching system, a plurality of cores having rectangular hysteresis loops, means for periodically applying such a large pulse of magnetizing force to all of the cores that at the end of the pulse all of the cores will be in one of the two saturated regions of the hysteresis loop, a plurality of selectively activatable inputs, a series circuit in series with each input, a source producing pulses during the spaces between said first-named pulses and feeding its pulses through each of said series circuits via activated ones of said inputs, another series circuit connected to said source to receive pulses synchronously with said previously mentioned series circuits, said series circuits having coils on said cores, said coils having such numbers of turns and winding directions that during each space between the first-named pulses all cores are switched to their other saturation regions except one of the cores, with the core which is not switched depending on which combination of inputs is activated.

2. A switching system as deiined in claim l in which there is a rectier in series with each input, and biasing means to cut off each rectifier to prevent current ilow therethrough except when the input is activated.

3. In a switching system, at least four cores having substantially square hysteresis loops, at least two inputs, a series circuit for each input, means for applying spaced pulses of magnetizing force which will leave each core in one Vsaturation regionof its hysteresis loop and for applying power pulses to said inputs during the spaces between said first-named pulses, each input including means for controlling the flow of pulses through its associated series circuit, the series circuit associated with one of the inputs having coils on the first and second cores which produce magnetizing forces tending to switch the cores from said one to the opposite saturation region of the hysteresis loop and coils on the third and fourth cores for producing magnetizing forces in the same direction as the magnetizing forces of the rst-named pulses, the series circuit associn ated with another of the inputs having coils on the first and third cores which produce magnetizing forces tending to switch the cores from said one to the opposite saturation region of the hysteresis loop and coils on the second and fourth cores for producing magnetizing forces in the same direction as the magnetizing forces of the iirstnamed pulses, and means for applying magnetizing forces to the second, third and fourth cores synchronously with said power pulses with the magnetizing force applied to the second core being substantially equal and opposite to that produced in that core by the second series circuit and with the magnetizing force thus produced in the third core being substantially equal and opposite to that produced in that core by the first-named series circuit and with the magnetizing force thus produced in the fourth core being substantially equal and opposite to the combined magnetizing forces produced in that core by both the rst and second series circuits when they are concurrently energized.

4. In a switching system as defined by claim 3, a rectiiier in each of said series circuits, and means to normally bias each rectifier to cut ott.

5. A switching system as deiined in claim 3, having output coils on all of said irst, second, third and fourth cores, a series circuit for each output coil, each series circuit including in addition to the output coil a rectiiier and a load.

6. A switching system as defined in claim 3 in which the first-named means includes a separate circuit for each of the first, second, third, and fourth cores, each separate circuit including a coil on the core, a rectiiier in series with the coil and a load, said first-named means also including a pulse generator for supplying pulses to said separate circuits whereby said coils will apply magnetizing forces to said cores which will leave each core in said one saturation region of its hysteresis loop.

7. A switching system comprising a plurality of cores having saturated and unsaturated operating regions and capable of assuming stable remanence conditions, rst winding means coupled to said cores, second Winding means coupled to certain of said cores but not to all of said cores, a source of regularly spaced alternately occurring positive and negative going pulses, irst rectier means coupling said first winding means to said source whereby rst polarity exursions of said source set all of said cores to one of their saturated regions, second rectifier means coupling said second winding means to said source, said second rectifier means being poled oppositely to said iirst rectifier means whereby opposite polarity excursions of said source tend to switch those cores having said second winding means coupled thereto through their unsaturated operating regions toward their other saturated regions, a plurality of input windings carried by said cores, said input windings being wound to aid certain of said second Winding means and to oppose others of said second winding means, and means lfor applying input pulses to selected ones of said input windings in coincidence With selected opposite polarity excursions of said source, said input windings and said second winding means coacting so that for each of the various possible combinations of pulsed input windings all but one of said cores are switched to their said other saturated region during times intermediate the occurrence of said irst polarity excursions of said source.

8. The combination of claim 7 including output means on each of said cores, said output means including means responsive to the switching of said cores from their one to their other saturated region for producing an output during said switching.

9. The combination of claim 7 including output means on each of said cores, said output means including means operative subsequent to switching of said cores for producng output signals related to which of said cores have` been switched from their one to their other saturated region. l

10. In a switching system, a plurality of cores capable of assuming stable remanence conditions, lirst winding means on said cores, rst pulse supply means coupled to said lirst winding means for periodically subjecting all said cores to a lrst pulse-type magnetomotive force thereby to cause all said cores to periodically reside at a first one of their remanence conditions, second winding means on certain of said cores and third winding means on said cores, second pulse supply means coupled to said second winding means for impressing second pulse-type niagnetomotive forces on cores having said second winding means thereon, input means for coupling said second pulse supply means to selected portions of said third winding means thereby to impress third pulse-type magnetomotive forces on said cores in coincidence with said second magnetomotive forces, said second and third magnetomotive forces coacting to switch all but one of said cores to their second remanence conditions, said second remanence conditions being of opposite magnetic polarity to said rst remanence conditions, said second pulse supply means and said input means being operative -for a limited period of time intermediate successive spaced applications of said first pulse-type magnetomotive forces to said cores, and output means coupled to all said cores for producing a significant output signal from the unswitched one of said cores, said output signal having a duration substantially equal to Said limited period of time.

l1. In a switching system, a plurality of cores formed from magnetic material capable of assuming stable remanence conditions and exhibiting a hysteresis loop having saturated and unsaturated regions of operation, a source of regularly occurring positive and negative going pulses, a first series circuit comprising a winding on each of said cores, a second series circuit comprising a plurality of further windings carried by certain cores but not all of said cores, first rectier means coupling said source to said rst series circuit whereby iirst polarity excursions of said source apply a pulse of magnetizing force to all of the cores, of magnitude suicient to drive all of the cores into one of the saturated regions of their hysteresis loops, Second rectifier means poled oppositely to said rst rectier means and coupling said source to said second series circuit whereby second polarity cX- cursions of said source apply a pulse of magnetizing force to those cores having windings thereon included in said Vsecond series circuit, of magnitude suicient to nullify the eiect of the pulses applied by said rst polarity excursions of said source to said rst series circuit, a plurality of input windings carried by said cores, said input windings being wound to aid the effect of certain of said further windings and to oppose the effect of others of said further windings, and a plurality of input means for applying current pulses to selected ones of said input windings in coincidence with selected second polarity excursions of said source, said input windings coacting with said further windings so that for each of the various possible combinations of pulsed input windings, all of said cores except a selected one are switched to the opposite saturated region of their hysteresis loops.

l2. A switching system as defined in claim 1l including an output coil on each core into which potential is induced when the core is switched, a series circuit for each output coil, each series circuit including the output coil, a rectifier and a load.

13. In a switching system, a plurality of cores formed from magnetic material capable of assuming stable remanence conditions and exhibiting a hysteresis loop having saturated and unsaturated regions of operation, a source of regularly occurring positive and negative going pulses, a rst series circuit comprising a winding on each of said cores, a second series circuit comprising a plurality of further windings carried by certain cores but not 7 all of said cores, first rectier means coupling said source to said rst series circuit whereby rst polarity excursions of said source apply a pulse of magnetizing force to all of the cores, of magnitude suicient to drive all of the cores into one of the saturated regions of their hysteresis loops, second rectifier means poled oppositely to said lirst rectifier means and coupling said source to said second series circuit whereby second polarity excursions of said source apply a pulse of magnetizing force to those cores having windings thereon included in said second series circuit, of magnitude sufficient to nullify the eiiect of the pulses applied by said' first polarity excursions of said source to said' irst series circuit, a plurality of input windings carried by said cores, said input windings being wound to aid the effect of certain of said further windingsv and to oppose the effect of others of said further windings, and a plurality of input means for applying current pulses to selected ones of said input windings in coincidence with selected second polarity excursions of said source, said input windings coacting with said further windings so that for each, of the various possible combinations of pulsedV input windings all of said cores except a selected one are switched to the opposite saturated region of their hysteresis loops, said plurality of input windings beinginterconnected in a plurality of series input circuits, one for each input, each series input circuit having a coil on each core.

14. In a switching system, a plurality of cores formed from magnetic material capable of assuming stable remanence conditions and exhibiting a hysteresis loop having saturated and unsaturated regions of operation, a source of regularly occurring positive and negative going pulses, a rst series circuit comprising a winding on each of said cores, a second series circuit comprising a plurality of further windings carried by certain cores butv not all of said cores, irst rectifier means coupling said source to said first series circuit whereby iirst polarity excursions of said source apply a pulse of magnetizing force to all of the cores, of magnitude suricient to drive all of the cores into one of the saturated regions of their hysteresis loops, second rectifier means poled oppositely to said iirst rectifier means and coupling said source to said second series circuit whereby second polarity excursions of said source apply a pulse of magnetizing force to those cores having windings thereon included in said second series circuit, of magnitude sutlicient to nullify the effect of the pulses applied by said first polarity excursions of said source to said firstl series circuit, a plurality of input windings carried by said cores, said input windings being wound to aid the effect of certain of said further windings and to oppose the effect of others of said further windings, a plurality of input means for applying current pulses to selected ones of said input windings in coincidence with selected second polarity excursionsV of said source, said input windingscoacting with said further windings so that for each of the various possible cornbinations of pulsed input windings all of said cores except a selected one are switchedto the opposite saturatedregion of their hysteresis loops, a further sourceof pulses for regularly producing spaced pulses between selective polarity excursions of the iirst mentioned .pulse source, and a plurality of output circuits in parallel with each other, all energized from said further source, and having one such output circuit for each core and each outputcircuit including the following in series: a rectifier, an output coil on the core, and a load, said series output circuits having suchV electrical characteristics that the switching system has gain whereby the output at the selected load has a greater power change than is required to switch the cores.

15. In a switching system a plurality ofV cores capable of assuming stable remanence conditions each corefhaving a binary address associated therewith, first windings on said cores, bias windings on certain of said cores and input windings on said cores, a first pulse source coupled to said first ywindings for periodically subjecting all of said cores to magnetomotive force in a first, direction thereby setting all of said cores periodically at a lirstone oftlieir remanence conditions, a plurality of input lines, there being asingle input line for each digit of the binary address, each input line being linked to all of the, cores via said control windings on said cores, a bias line linking all those cores having, at least one one in their address Via said bias windings on said certain cores, a second pulse source coupled to said bias line and selectively coupled to said input lines, the presence of a one in the binary address being represented by a pulse applied to the corresponding input line from said second pulse source and the presence of a zero in the binary address being represented by the absence of a pulse on the corresponding input line, each control winding in a given input line being wound in a direction about each core whereby the application of a pulse tends to set the core to its second remanent condition if the input line represents an address digit which for that core is zero and tends to inhibit the setting of the core to its second remanent condition if the input line represents an address digit which for that core is one, said bias windings. beingA wound in a direction about the cores whereby the application of a pulse tends to set the cores to their secondremanent condition, each bias Winding having sufficient turns to give a magnetomotive force of +NF where N is the number of ones in the address of the corresponding core and '-l-F is the magnetomotive force required to set a core, whereby the application of a pulse from said second pulse source is effective to set all of the cores except a single selected core to their second remanent condition.

16. In a switching system as in claim 15, output means associated with each core comprising a further winding coupled to saidV second pulse source and to a load whereby a significant outputY signal is obtained from said single selected core on application of a pulse from said second pulse source.

References Cited in the tile of this patent UNITED STATES PATENTS 2,691,152 Williams Oct. 5, 1954 2,691,153 Rajchman Oct. 5, 1954 2,729,807 Paivinen Jan. 3, 1956 2,735,860v Rajchrnan Feb; 7, 1956 V21,734,182 Rajchrnan Feb. 7, 1956 2,734,183 Rajchman Feb.l 7, 1956 OTHER REFERENCES Publicationl: Magnetic Matrix Switch Reads Binary Output (Brean) Electronics, May 1954, pp. 157 to 159 (Figures 2 and 3 relied on pages 158 and 159). 

